During the last two years, we have developed structural models of the transmembrane and extracellular segments of Shaker, KvAP, hERG, NaChBac, and Ca2+ channels in resting, open, and numerous transition conformations. Molecular dynamic simulations of these channels embedded in a lipid bilayer were performed to evaluate and refine the models. The models were constrained by recently obtained experimental data; e.g., the crystal structure of the Kv1.2 channel, electron paramagnetic resonance (EPR) studies of KvAP channels, thermodynamic cyclic mutagenesis studies of the binding of BeKM1 toxin from scorpions to the hERG channel, and cysteine scanning mutagenesis (SCAM) studies of Ca2+ channel pores. We have demonstrated that the 'helical screw' model for the voltage-dependent movement of the S4 voltage-sensor segment that we proposed first in 1986, is consistent with virtually all experimental results and energetic criteria, including analyses using molecular dynamic simulations. Recent experimental and computational studies from other groups have provided additional support for our models. The NaChBac channel is a prokaryotic Na+ channel that has similarities to K+, Ca2+, and Na+ channels. We were the first group to identify this sequence in the prokaryotic sequence data base. Since then, it has been expressed and its properties have been studied expensively. Efforts are underway to solve its crystal structure. Our NaChBac was develop using the crystal structure of the Kv1.2 channel as an initial template. The resulting NaChBac model has several unique features involving the ion selective region formed by the P segments, the activation gate formed by the S6 segment, and the interaction between the voltage-sensing (S1-S4) and pore-forming (S5-P-S6) domains. We are now using the NaChBac model as a stepping stone to model more complex eukaryotic Ca2+ and Na+ channels. So far we have modeled the transmembrane regions of human and fungal Ca2+ channels. We are collaborating with Steffen Herring's and Angie Gelli's groups to test experimentally these models. Specifically, we are using the models to analyze the molecular pharmacology of Ca2+ channel blockers (important in treating hypertension and heart disease in humans and potentially important as antifungicides) and to better understand how mutations associated with genetic diseases alter the gating properties of Ca2+ channels. Manuscripts have been submitted on our models of NaChBac and human Ca2+ channels. We have started a new project to develop structural and functional models of channel families [EAG and ERG, AKT (plant), PAK (paramecium), CNG, and HCN] that possess a cyclic nucleotide domain. Substantial progress has been made in modeling the hERG and HCN channels. A crystal structure of the cyclic nucleotide-binding domain of the HCN channel is being used to model the cytoplasmic domain. We are focusing on this group of families because expression of some of them (especially EAG channels that are closely related to hERG channels) has been associated with several cancers. We are collaborating with Gea-Ny Tseng's lab to experimentally test aspects of our hERG channels.